KPL/FK Chandrayaan-1 Frames Kernel ======================================================================== This frame kernel is based on a preliminary template provided by ISRO, which only contained the description of the Chandrayaan-1 spacecraft frame itself. Descriptions of the SIR2 and the SARA instruments have been added by Bjoern Grieger, ESA/SRE-OS, +34 91 81 31 107, bgrieger@sciops.esa.int. Chandrayaan-1 Mission NAIF ID Codes -- Summary Section ======================================================================== The following names and NAIF ID codes are assigned to the Chandrayaan-1 spacecraft, its structures and science instruments (the keywords implementing these definitions are located in the section "Chandrayaan-1 Mission NAIF ID Codes -- Definition Section" at the end of this file): Chandrayaan-1 Spacecraft and Spacecraft Structures names/IDs: CHANDRAYAAN-1 -86 CH1 -86 CH1_SPACECRAFT -86000 SIR2 names/IDs: CH1_SIR2 -86700 SARA names/IDs: CH1_CENA -86600 CH1_SWIM -86610 Chandrayaan-1 Frames ======================================================================== The following Chandrayaan-1 frames are defined in this kernel file: Name Relative to Type NAIF ID ====================== =================== ============ ======= CH1_SPACECRAFT J2000 CK -86000 SIR2 Frames: ------------ CH1_SIR2 CH1_SPACECRAFT FIXED -86700 SARA Frames: ------------ CH1_CENA CH1_SPACECRAFT FIXED -86600 CH1_SWIM CH1_SPACECRAFT FIXED -86610 Frame Tree ======================================================================== The diagram below shows the frame hierarchy for the Chandrayaan-1 spacecraft and its structure frame. "J2000" INERTIAL +-----------------------------------------------------+ | | | |<-pck |<-ck |<-pck | | | V | V "IAU_MOON" | "MOON_PA" MOON BFXD | MOON HIGH-PREC BFXD ------------- | ------------------- | | | | | "CH1_SN1/2" | ----------- | ^ | | | |<-fixed | | V | "CH1_SPACECRAFT" +-----------------------------------------------------+ | | | | |<-ck |<-ck |<-fixed |<-fixed | | | | V V V V "CH1_SA_GIMBAL" "CH1_HGA_GIMBAL" "CH1_TMC" "CH1_LLRI" --------------- --------------- ------------ ---------- | | | | |<-fixed |<-fixed |<-fixed |<-fixed | | | | V V V V "CH1_SA" "CH1_HGA" "AFT" "NADIR" "FORE" "BEAM" "RECEIVER" -------- --------- ----- ------- ------ ------ ---------- CH1 Spacecraft Frame ======================================================================== CH1_SPACECRAFT J2000 CK -86000 CH1 Spacecraft Frame -------------------------------------- The CH1 spacecraft frame is defined as follows: - +Z towards solar array side -- positive or negative normal to orbit plane - +X is along instrument boresights - towards Moon - +Y towards MIP side -- along velocity or along anti-velocity - the origin of this frame is the launch vehicle interface point. These diagrams illustrate the CH1_SPACECRAFT frame: To be completed. Since the orientation of the CH1_SPACECRAFT frame is computed on-board, sent down in telemetry, and stored in the s/c CK files, it is defined as a CK-based frame. \begindata FRAME_CH1_SPACECRAFT = -86001 FRAME_-86001_NAME = 'CH1_SPACECRAFT' FRAME_-86001_CLASS = 3 FRAME_-86001_CLASS_ID = -86001 FRAME_-86001_CENTER = -86 CK_-86001_SCLK = -86 CK_-86001_SPK = -86 OBJECT_-86_FRAME = 'CH1_SPACECRAFT' \begintext SIR2 frames: ======================================================================== This section of the file contains the definitions of the SIR2 frames. SIR2 Frame Tree -------------------------------------- The diagram below shows the SIR2 frame hierarchy. "J2000" INERTIAL +---------------------------------------------------+ | | | | | | |<-pck | pck->| | | | V | V "IAU_MOON" | "IAU_EARTH" MOON BODY-FIXED | EARTH BODY-FIXED --------------- | ---------------- | |<-ck | V "CH1_SPACECRAFT" ---------------- | | | |<-fixed | V "CH1_SIR2" ---------- SIR2 Detector Frame -------------------------------------- Since the SIR2 detector receives radiation through a prism and essentially has a single pixel in terms of spatial resolution, its frame, CH1_SIR2, is orientated in such a way that the SIR2 boresight direction is nominally co-aligned with the spacecraft +X axis. The SIR2 Detector frame -- CH1_SIR2 -- is defined as follows: - +Z axis points along the camera boresight; - +X axis is nominally co-aligned with the s/c +Z axis; - +Y axis completes the right hand frame; - the origin of the frame is located at the fiber tip focal point. +X s/c side view: ----------------- ^ ____________|______________ | | | | |+Zsc |____________ | | | | | | | | | | | | | o---------> | | | +Ysc | | | | | | | ^ | | |___|_______| | | |+Xsir |_________________________|___|___ | | | <--------o | +Ysir |_____| +Xsc and +Zsir are out of page Exactly nominal mounting would require this rotation: Angles: ( 0.0, -90.0, 180.0 ) Axes: ( 1, 2, 3 ) Additionally to this rotation, we have to take into account devi- ations from the nominal mounting. The alignment values given below have been provided by SPACECRAFT ALIGNMENT SECTION MECHANICAL INTEGRATION DIVISION SIG, ISAC on 2008-Oct-31 in the form of two tables. This is the first table: +----------------------+-----------+----------------+----------------+ | | Rotation | Rotation | Rotation | +----------------------+-----------+----------------+----------------+ | | about YAW | about ROLL | about PITCH | +----------------------+-----------+----------------+----------------+ |Pre dynamic | - | - 0 deg0' 40'' | + 0 deg2' 35'' | +----------------------+-----------+----------------+----------------+ |Post dynamic | - | + 0 deg1' 07'' | + 0 deg2' 44'' | +----------------------+-----------+----------------+----------------+ |Difference (Pre-Post) | - | - 0 deg1' 47'' | - 0 deg0' 09'' | +----------------------+-----------+----------------+----------------+ It is noted that all the alignment values given are cube normals only. Cube errors are accounted for in the second table provided: +-------------+-----------+-------------------+-------------------+ | | Rotation | Rotation | Rotation | +-------------+-----------+-------------------+-------------------+ | | about YAW | about ROLL | about PITCH | +-------------+-----------+-------------------+-------------------+ |Post dynamic | - | - 0 deg8' 18.16'' | - 0 deg3' 12.53'' | +-------------+-----------+-------------------+-------------------+ Thus we take the values from the second table. These angles are so small that the sequence of rotations does not really matter, however, we assume that the required sequence of rota- tions is first yaw (which is zero), second pitch, third roll. We assume that the negative values indicate a left-handed rotation around the specified axes. Converted to degrees, we have this rotation angles: First rotation around PITCH: -0.05348055555555556 Second rotation around ROLL: -0.138377777777778 The above sequence and signs of rotations would transform the instrument from the nominal mounting position to the actual mounting position. In this kernel we have to provide the opposite transforma- tion, from the actual to the nominal position of the instrument. Thus we have to reverse the sequence of rotations and negate the angles: First rotation around ROLL: 0.138377777777778 Second rotation around PITCH: 0.05348055555555556 In the instrument frame's coordinate system --- this is the sys- tem in which the rotation axes have to be defined ---, this corre- sponds to First rotation around -Y: 0.138377777777778 Second rotation around +X: 0.05348055555555556 To replace -Y by +Y, we have to negate the angle, thus: First rotation around +Y: -0.138377777777778 Second rotation around +X: 0.05348055555555556 In SPICE encoding, this rotation is described by Angles: ( 0.05348055555555556, -0.138377777777778, 0.0 ) Axes: ( 1, 2, 3 ) This rotation transforms the instrument from the actual mounting to the nominal mounting. We have first to apply this rotation and then apply the rotation which transforms the axes of the instrument frame to the respective axes of the spacecraft frame. As stated above, this second rotation is described by Angles: ( 0.0, -90.0, 180.0 ) Axes: ( 1, 2, 3 ) To compute the combination of these two rotations we use the SPICE routines eul2m, mxm, and m2eul. The resultant rotation is Angles: ( -21.1305922, -89.8516471, -158.869343 ) Axes: ( 1, 2, 3 ) The resultant rotation is reflected in the below data section. \begindata FRAME_CH1_SIR2 = -86700 FRAME_-86700_NAME = 'CH1_SIR2' FRAME_-86700_CLASS = 4 FRAME_-86700_CLASS_ID = -86700 FRAME_-86700_CENTER = -86 TKFRAME_-86700_RELATIVE = 'CH1_SPACECRAFT' TKFRAME_-86700_SPEC = 'ANGLES' TKFRAME_-86700_UNITS = 'DEGREES' TKFRAME_-86700_ANGLES = (-21.1305922, -89.8516471, -158.869343) TKFRAME_-86700_AXES = ( 1, 2, 3 ) \begintext SARA frames: ======================================================================== This section of the file contains the definitions of the SARA frames. SARA Frame Tree -------------------------------------- The diagram below shows the SARA frame hierarchy. "J2000" INERTIAL +---------------------------------------------------+ | | | | | | |<-pck | pck->| | | | V | V "IAU_MOON" | "IAU_EARTH" MOON BODY-FIXED | EARTH BODY-FIXED --------------- | ---------------- | |<-ck | V "CH1_SPACECRAFT" ---------------- | +-------------------------+------------+ | | |<-fixed |<-fixed | | V V "CH1_CENA" "CH1_SWIM" ---------- ---------- SARA Detector Frame -------------------------------------- The SARA instrument comprises two sensors, CENA and SWIM. These sensors look in different directions, as CENA measures particles from the lunar surface while SWIM monitors the solar activety. However, the coordinate systems in which both sensors are defined are co-aligned. The different viewing direction are implemented through different boresight vectors. Although the co-ordinate systems of both sensors are co-aligned, we define two separate sensor base frames. For the time being, we assume nominal mounting of the sensors on the spacecraft, but if we later want to consider missalignment angles (which would be different for the two sensors), we need the seperate frames. The SARA instrument frames -- CH1_CENA and CH1_SWIM -- are defined as follows: - +X axis is nominally co-aligned with the s/c +Z axis; - +Y axis is nominally co-aligned with the s/c +X axis; - +Z axis is nominally co-aligned with the s/c +Y axis; +X s/c side view: ----------------- ^ ____________|______________ | | | | |+Zsc |_____________ | | | |_| ^ | | | |SWIM |+Xcena | | | |__ |+Xswim | o---------> | | | | | +Ysc | |_| o-------> | | |CENA +Zcena | | | +Zswim | |___________| | | |_________________________| +Xsc and +Ycena/+Yswim are out of page Aligning the CENA and SWIM frames with the spacecraft frame requires this rotation: Angles: ( 90.0, 0.0, 90.0 ) Axes: ( 1, 2, 3 ) The applicable rotations are reflected in the below data section. \begindata FRAME_CH1_CENA = -86600 FRAME_-86600_NAME = 'CH1_CENA' FRAME_-86600_CLASS = 4 FRAME_-86600_CLASS_ID = -86600 FRAME_-86600_CENTER = -86 TKFRAME_-86600_RELATIVE = 'CH1_SPACECRAFT' TKFRAME_-86600_SPEC = 'ANGLES' TKFRAME_-86600_UNITS = 'DEGREES' TKFRAME_-86600_ANGLES = ( 90.0, 0.0, 90.0 ) TKFRAME_-86600_AXES = ( 1, 2, 3 ) FRAME_CH1_SWIM = -86610 FRAME_-86610_NAME = 'CH1_SWIM' FRAME_-86610_CLASS = 4 FRAME_-86610_CLASS_ID = -86610 FRAME_-86610_CENTER = -86 TKFRAME_-86610_RELATIVE = 'CH1_SPACECRAFT' TKFRAME_-86610_SPEC = 'ANGLES' TKFRAME_-86610_UNITS = 'DEGREES' TKFRAME_-86610_ANGLES = ( 90.0, 0.0, 90.0 ) TKFRAME_-86610_AXES = ( 1, 2, 3 ) \begintext \begindata NAIF_BODY_NAME += ( 'CHANDRAYAAN-1' ) NAIF_BODY_CODE += ( -86 ) NAIF_BODY_NAME += ( 'CH1' ) NAIF_BODY_CODE += ( -86 ) NAIF_BODY_NAME += ( 'CH1_SPACECRAFT' ) NAIF_BODY_CODE += ( -86001 ) \begintext SIR2 IDs -------------------------------------- This table summarizes SIR2 IDs: Name ID --------------------- ------- CH1_SIR2 -86700 Name-ID Mapping keywords: \begindata NAIF_BODY_NAME += ( 'CH1_SIR2' ) NAIF_BODY_CODE += ( -86700 ) \begintext SARA IDs -------------------------------------- This table summarizes SARA IDs: Name ID --------------------- ------- CH1_CENA -86600 CH1_SWIM -86610 Name-ID Mapping keywords: \begindata NAIF_BODY_NAME += ( 'CH1_CENA' ) NAIF_BODY_CODE += ( -86600 ) NAIF_BODY_NAME += ( 'CH1_SWIM' ) NAIF_BODY_CODE += ( -86610 ) \begintext